The study links specific types of abuse with symptoms experienced by many survivors later in life.

The research, which was published in the American Journal of Psychiatry, imaged the brains of 51 women in Atlanta who were taking part in a larger project on the effects of early trauma.

Twenty-eight of the participants had been seriously maltreated as children, suffering from various combinations of neglect and emotional, physical and sexual abuse. The other 23 experienced either no maltreatment or next to nothing. The women ranged in age from 18 to 45, but the average age was 27.

A standard questionnaire on childhood trauma was used to assess the women's early-childhood experiences, and their brains were scanned to measure the thickness of various regions of the cortex.

Cortical thickness is linked to brain development, with thicker regions generally suggesting healthier growth. Brains, like muscles, develop through use -- so regions that have been "exercised" more tend to be bigger.

But abuse can interfere with development. To cope with overwhelming experiences of distress, the brain can alter patterns of signaling from the pathways involved, which can ultimately leave those regions underdeveloped from reduced input. The brain of a child who is raped, for example, may react by reducing the connectivity of the regions that were hurt.

"If abuse was of a sexual type, we saw changes in the somatosensory cortex, the area that processes input from the body to create sensations and perceptions," says Jens Pruessner, associate professor of psychiatry at McGill University in Montreal.

Somatosensory areas create a map of the body on the brain, with each region processing sensation from specific body parts. As compared with nonabused women, "women who were sexually abused had thinning in the area where the genitalia were located," he says.

Although the prevalence varies depending on the severity and the amount of abuse, many sexual-abuse survivors report sexual problems in adulthood, including reductions in desire and sensation; sometimes they suffer from chronic genital pain.

"There are some studies suggesting that thinning of the cortex (in these regions) would be associated with a lowered pain threshold, so you would more easily perceive pain instead of touch from that area," says Pruessner. Some of the women showed cortical thinning in regions associated with the face and mouth, which could result from abuse to those areas.

Emotional abuse left a different type of scar. Here, the changes were seen in regions associated with understanding and controlling emotions and recognizing and responding to the feelings of others.

"We (saw thinning) in areas that have to do with self-awareness and emotional regulation, areas in the prefrontal cortex and medial temporal lobe, which typically show activation when people are asked to think about themselves or reflect on their emotions," Pruessner says.

Emotional abuse can leave its victims prone to depression, moodiness and extreme or dulled emotional responsiveness, depending on the person and the particular circumstances. "As adults, (they have difficulty) reflecting on themselves and finding the right way to deal with emotions," says Pruessner.

"If replicated, these data provide compelling evidence about the enduring structural effects on the brain as a function of early life experience," Dr. Maria Oquendo, a professor of clinical psychiatry at Columbia University, and her colleagues wrote in an editorial accompanying the study.

This study didn't follow the women from childhood, so it can't prove that the abuse caused the changes in these regions. It's possible, for example, that thinning in these brain regions results from later avoidance of healthy experience -- abstaining from sex even in a good relationship, for example -- rather than from the initial abuse.

In both emotional and sexual abuse, a decrease in connectivity of regions that are overwhelmed by maltreatment may be interpreted as a self-protective response. But it can ultimately prove harmful because it interferes with subsequent healthy sensation and experience.

The changes seen were not small: Pruessner says if a region typically was 5 millimeters thick on average, in abuse survivors it was just 3 to 4 millimeters. "The effect size was quite significant," he adds.

But that doesn't mean that recovery is impossible. Most abuse survivors do not develop symptoms, in fact, and research shows increasingly that the brain can change dramatically when provided with the right type of support and emotional nourishment.

Understanding what goes wrong during and after abuse, the researchers believe, will help them figure out how to make it right. "That is our long-term hope," Pruessner says.